A sarcastic way of saying that the proposition was unfortunately not going to be accepted.

Ma Sheila's famous comment when Ian Leslie on ?60 Minutes,told her that 'We', the Australian people in the town in Western Australia near where there was a commune of 'Orange People', did not want the Orange People there. She replied, "What can I say. Tough titties"
The previously current expression that I think she was trying to quote was, "Tough Bikkies".
Her reply largely took over from that.